Sander drum



Aug.16,1927. l y1,639,155 Y R. A. WILLIAMS ET AL SANDER DRUM Filed March6 1926 Patented Aug. v16, 1927.

UNITED 'sr-AT Es RICHARD A. WILLIAMS AND wAL'rnRYL. BIGsBY, ory BELoI'T,WISCONSIN, AssIeNoBs TO YA'IEEIS-AMERICAN'v MACHINE COMPANY, OFBELOI'I,Y WISCONSIN, A"COBPORA TION OF DELAWARE.

SANDER DRUM.

Application flied March e, 192s. serial No. 92,672.

This invention has to do with sander drums of the type in which thecovering of sand paper ory other material isr wound spirally on thedrum. i

The principal object of the invention is to provide, in such afdrum, animproved mechanism for initially tensioning the covering on the drum andthereafter taking up the slack which develops in the covering while inservice..

. Other objects and advantages of the invention will be evident upon afull understanding ot the construction, arrangement and operation of themechanism.

One form of the invention is herein presented tor the purpose ofexemplitication7 but it will bev understoodthat theinvention is alsosusceptible of embodiment in other modied forms coming equally withinthe scope of the appended claims. j

In the accompanying drawing, Fig. 1 is a sectional view through a drumequipped with the mechanism of the invention, Fig. 2

is a somewhat similar view produced on a' larger scale, and Fig. 3 is anaxial view of the drum with the near end plate removed.-

The drum illustrated in the Adrawing consists of a shaft 10, a number ofcylindrical sections 11 which are iiXedly mounted O n the shaft, and twoend plates 12 and 13 which are loosely mounted on the shaft at the endsof the sections. The covering ot sand paper or other material (notshown) is wound spirally about the body of the drum overa lining of feltor other material (also not shown), and is secured in a suitable mannerto the peripheral portions ot the end plates 12 and 13, which plates areso mounted on the shaft as to be movable spira-ily therealong inopposite directions whereby to place the covering under tension.

A gear 14 is journalled on the hub'15 of.

the section which adjoins the end plate 12, and is provided with asleeve 16 which is in screw-threaded engagement with the hub 17y of theend plate 12. Another gear 18 is journalled on the hub 19 of the sectionwhich adjoins the other end plate 13, and is provided with a sleeve 2Owhich is in screwthreaded engagement with the hub 21 of an intermediateplate 22. The plate 13 is held in spaced relation to the plate 22 bymeans of a number of compressedcoil springs 23;,

Iwhich springs encompass studs 24 screwed into the plate 13 and seatwithin cup-shaped casings 25 carried bythe pla`te`22 over aperf turesthere-in. The studs 24 pass through apertures in the bottoms of thecasings255 andare headed over beyond. the bottoms whereby to engagetherewith. and limitthe extent to which the springs 23 can separate theplate13fro'm the yplate 22. v i.

`The threads 26ibetween the gear18 and the intermediate plate 22 areopposite in direction to the threads 27`between the gear 14 and the endplate 12, and are substantially greater in. pitch, the pitchesbeingprefer ably in about the ratio of two to one. Itis in this feature ofthemechanism that the invention primarily resides.

AEach oi'Y the end lates 12.*and' is provided with a projection 28`which extends within the body of' the drum and is'diagonally slottedat29 to. engage with a stud 30 on the inner wall V,of the body. The pinand slot connections described cause the end plates 12 and 13 to movespirally in opposite directions away from the body of the drum whenseparative movement is imparted thereto by rotation of the gears 14 and18. rI'wo small pinions 31 and 32 mesh respectively with the gears 14and 18, and are iXedly mounted on a shaft 33 which is journalled in thebody of the drum. One end of the shaft 33 is positioned just in -lwardly of the end plate 13,l and is provided with a polygonal portion 34which may be engaged by a socket wrench inserted through an aperture 35in the plate `13.

- It is quite important that the weight of the parts of .thel mechanismin the drum be counterbalanced relative to the axis of rotation, and theweight of the pinions 31 and 32 and shaft 33 at one side of the drum isaccordingly neutralized by the weight of a rod 36 which is positioned inthe drum in diametrically opposed relation to the shaft 33. The rod 36also serves as a support for two gear-positioning members 37 and 38'which are adjustably mounted on the ends 'of the rod and bear againstthe outer side Jfaces of the gears 14 and 18 whereby to position thesame on the hubs 15 and'19.

When the shaft 33 is rotated in a 'clockwise direction, as viewed inFig.'3, the pinions 31 and 32 will cause the gears 14 and 18 to rotatein a. countercloclnvise direction. The gear 14C Will thereupon screw theend plate 12 outwardly in a spiral clockwise path defined by the pin andSlot connection bet'w'een the plate and the body of the drum, andthegear 18 Will screw the Vintermediate plate 22 outwardly, causing theplate 22 to push before it the end plate 13 in a spiralcountercloclrwise path. rThe plate 22, however, Will move at a muchgreater rate of speedv thantlie plate 12 because` ot the dit- 'lerenceinV pitch between the threads on the gear 14- andr those on the gear 18,with the result that the end loit the covering' .attached to they` plate13 Will receive the proper amount of tensioning before `the end a tachedto the plate 12 does, and the springs 23 between the plates 13 and 22Will as a consequence yield.` as the plate 22 continues to moveoutwardly.v Y

Then the covering has received the proper amount of tensioningthroughout the length ot the drum, the drum is ready for use. AfterY thedrum lias'been in service for a time, slack will tend to develop towardthe rear end of the spirally Wound Covering, whichv end is attached tothe plate 13, but, as fast as such slack develops, it `Will beautomatically tale'n up by further spiral movement ot the plate 13 underthe expanding action of the compressed springs 23.

yieldable. member moving,` at a greater rate oil speed than the othermember.

2, A sander drum, comprising a body on which a covering ot' sandpaperror other material is adapted to be spirally Wound, two members to'which the ends of the 'covering' are adapted to be secured, connectionsbetween the members and the body for limiting` the members' only tospiral movement in opposite directions relative to the body, tvvo gearsjournalled Witliinthe body, means operable from exteriorly of the bodyfor rorating the gears, a screvvthreaded connection between one gear andone member, and ascreuhthreaded connection of substantially lgreaterpitch between the other gear and tne other member.'

In testimony whereof We have hereunto lsul'iscribed our names.

RICHARD A. l/VLLL-YVS. VALTER L. BIGSBY.

